BALL or BALLE, WILLIAM (d. 1690), astronomer, was the eldest of seventeen children born to Sir Peter Ball, knight, recorder of Exeter and attorney-general to the queen in the reigns of Charles I and Charles II, by Ann, daughter of Sir William Cooke, of Gloucestershire, his wife. In 1638, when William Ball was probably about eleven years of age, Robert Chamberlain, a dependant of his father, dedicated his 'Epigrams and Epitaphs' to him in the character of a precocious poet. His observations and drawings of Saturn from 5 Feb. 1656 to 17 June 1659 (communicated by Dr. Wallis) are frequently cited by Huygens (Op. Varia, iii. 625-6) as confirmatory of his own, in his 'Brief Assertion' (1660) of the annular character of the Saturnian appendages against the objections of Eustachio Divini. Ball joined the meetings of the 'Oxonian Society' at Gresham College in 1659, co-operated in founding the Royal Society in the following year, and was named, in the charter of 15 July 1662, its first treasurer. On his resignation of this office, 30 Nov. 1663, he promised, and subsequently paid to the funds of the society, a donation of 100l. (Weld, Hist. Royal Soc. i. 171). Soon after 15 June 1665, when he was present at a meeting of the Royal Society (Birch, Hist. Royal Soc. i. 439), he appears to have left London, and resumed his astronomical pursuits at his father's residence, Mamhead House, Devonshire, about ten miles south of Exeter. Here, at six p.m. 13 Oct. 1665, he made, in conjunction with his brother, Peter Ball, M.D., F.R.S., an observation which has acquired a certain spurious celebrity. He described it in the following sentence of a letter to Sir Robert Moray, which was accompanied by a drawing; the words were inserted in 'No. 9 of the 'Philosophical Transactions' (i. 153):

'This appear'd to me the present figure of Saturn, somewhat otherwise than I expected, thinking it would have been decreasing; but I found it full as ever, and a little hollow above and below. Whereupon,' the report continues, 'the person to whom notice was sent hereof, examining this shape, hath by letters desired the worthy author of the "Systeme of this Planet" [Huygens] that he would now attentively consider the present figure of his anses or ring, to see whether the appearance be to him as in this figure, and consequently whether he there meets with nothing that may make him think that it is not one body of a circular figure that embraces his diske, but two.'

Owing to some unexplained circumstance, the plate containing the figure referred to was omitted or removed from the great majority of copies of the 'Philosophical Transactions,' and the letterpress standing alone might naturally be interpreted to signify that the brothers Ball had anticipated by ten years Cassini's discovery of the principal division in Saturn's ring. This merit was in fact attributed to them by Admiral (then Captain) Smyth in 1844 (A. Cycle of Celestial Objects, p. 51), and his lead was followed by most writers on astronomical subjects down to October 1882, when Mr. W. T. Lynn pointed out, in the 'Observatory,' the source of the misconception. In the few extant impressions of the woodcut from Ball's drawing not the slightest indication is given of separation into two concentric bodies, but the elliptic outline of the wide-open ring is represented as broken by a depression at each extremity of the minor axis. Sir Robert Moray's suggestion to Huygens seems (very obscurely) to convey his opinion that these 'hollownesses' were due to the intersection of a pair of crossed rings. Their true explanation is unquestionably that Ball, though he employed a 38-foot telescope with a double eyeglass, and 'never saw the planet more distinct,' was deceived by an optical illusion. The impossible delineations of the same object by other observers of that period (see plate facing p. 634 of Huygens's Op. Varia, iii.) render Ball's error less surprising. Indeed, it was anticipated at Naples in 1633 by F. Fontana (Novæ Obsercationes, p. 130; see Observatory, No. 79, p. 341).

Pepys tells us (Bright's ed. v. 375) that Ball accompanied him and Lord Brouncker to Lincoln's Inn to visit the new Bishop of Chester (Wilkins) 18 Oct. 1668, and he was one of a committee for auditing the accounts of the Royal Society in November following. He succeeded to the family estates on his father's death in 1680, and erected a monument to him in the little church of Mamhead. He died in 1690, and was buried in the Round of the Middle Temple 22 Oct. of that year (Temple Register; cf. Letters of Administration P. C. C., by decree, 14 Jan. 1692). He married Mary Posthuma Hussey, of Lincolnshire, who survived him, and had by her a son, William. The last of the Balls of Mamhead died 13 Nov. 1749.

[Prince's Worthies of Devon (1701), 111-3; Polwhele's Hist. of Devonshire (1797), ii. 155-7; Watt's Bibl. Brit. i. 67; Prof. J. C. Adams (Month. Not Royal Astr. Soc. Jan. 1883, pp. 92-7) attempts to prove that Ball's observation was misrepresented, both in the plate (cancelled, as he suggests, on that account) and in the letterpress of Phil. Trans. See, on the other side, Vivian in Month. Not. March 1883, and Lynn, in Observatory, 1 June and 1 Oct. 1883. Prof. Bakhuyson of Leyden gives, Observatory, 2 July 1883, the passage from Moray's letter to Huygens referred to in Phil. Trans. i. 153. Huygens's reply has not yet been brought to light.]